Northern District of California Applies ERISA Equitable Estoppel to Enforce Longstanding Misrepresentations of Pension Eligibility

In Woo v. Kaiser Found. Health Plan, Inc., No. 23-cv-05063, 2026 WL 194578 (N.D. Cal. Jan. 26, 2026), the Northern District of California granted judgment for a plan participant on her ERISA § 502(a)(3) equitable estoppel claim, holding that Kaiser was estopped from denying her participation in a defined benefit pension plan and related supplemental retirement plan after more than a decade of repeated misrepresentations regarding her eligibility.

The plaintiff transferred positions in 2009 in a manner that, under the plan’s governing documents and applicable collective bargaining agreement, ultimately rendered her ineligible to participate in the Kaiser Permanente Employees Pension Plan (“KPEPP”) and its after-tax Supplemental Retirement Income Plan (“SRIP”) beginning in 2010. Nevertheless, Kaiser’s agents repeatedly confirmed her eligibility, credited her with years of service, provided benefit estimates, and allowed her to make voluntary contributions for over ten years. Kaiser first informed her of her alleged ineligibility in 2020 following an internal audit. After Kaiser denied her administrative claim, Woo sued seeking equitable estoppel.

Following a Rule 52 bench trial on the administrative record, the court ruled in Woo’s favor and addressed each element of ERISA equitable estoppel in turn.

Material Misrepresentation
The court held that Kaiser materially misrepresented Woo’s eligibility to participate in the KPEPP and SRIP over an extended period. Vanguard and the Kaiser Permanente Retirement Center (“KPRC”)—entities tasked with plan enrollment, account administration, and participant communications—had apparent authority to convey eligibility determinations on Kaiser’s behalf. While some benefit estimates contained disclaimers, other communications unequivocally stated that Woo was an active participant, credited her with years of service, and confirmed her continued accrual of pension benefits. The court characterized these statements as misleading half-truths that required correction once her eligibility allegedly changed.

Reasonable and Detrimental Reliance
The court found that Woo reasonably and detrimentally relied on Kaiser’s representations. She accepted and remained in her Northern California position, engaged in long-term retirement planning, and structured her career and finances based on the belief that she would receive defined pension benefits. Kaiser’s later offer to make corrective 401(k) contributions did not cure the harm, particularly given Woo’s career stage and the fundamentally different nature of the retirement benefits.

Extraordinary Circumstances
Extraordinary circumstances were present because Kaiser repeatedly misrepresented Woo’s eligibility over more than a decade. The court emphasized that sustained, consistent misrepresentations over time constitute a paradigmatic case for equitable estoppel under Ninth Circuit precedent.

Ambiguous Plan Provisions
The court concluded that the plan documents were ambiguous as applied. Although certain provisions excluded employees in Woo’s position, other provisions stated that eligibility determinations made by the participating employer were “conclusive and binding.” The interaction between those provisions reasonably supported competing interpretations, particularly where Kaiser initially determined Woo to be eligible and repeatedly reaffirmed that determination. Estopping Kaiser from reversing course did not contradict the plan’s written terms but instead gave effect to the provision making employer eligibility determinations binding.

Representations Involving Interpretation of the Plan
Finally, the court held that Kaiser’s representations involved interpretations of the plan, not mere ministerial statements. By confirming Woo’s eligibility and ongoing accrual of credited service, Kaiser adopted and communicated an interpretation of the plan that treated the employer’s eligibility determination as controlling. Because that interpretation was plausible under the plan’s ambiguous terms, enforcing it through equitable estoppel was permissible under ERISA.

Holding
The court granted Woo’s motion for judgment and denied Kaiser’s cross-motion, estopping Kaiser from precluding Woo’s participation in the KPEPP and SRIP.